1. Field of the Invention
The invention relates to a process for the production of organically modified high-molecular-weight siloxane polymers.
2. Description of the Related Art
U.S. Pat. No. 6,759,094 B2 describes organically modified high-molecular-weight siloxane polymers which are synthesized via double hydrosilylation: In a first stage, branched SiH-terminated siloxane polymers are constructed which, in a subsequent reaction with aliphatically unsaturated organic compounds, are functionalized on the SiH ends again via hydrosilylation. Very high-molecular-weight siloxane polymers are obtainable via this reaction cycle, although the average number of organic substituents per molecule is limited by the number of SiH ends of the precursor. In the case of very high functionalization there is a gel risk and the production of high-molecular-weight siloxane polymers with terminal organic substituents is in principle not possible.
U.S. Pat. Nos. 5,981,681 and 5,807,956 also describe the production of high-molecular-weight siloxane polymers which are produced from telechelic diepoxysiloxanes and diaminopolyethers and have a linear block structure. The synthesis requires exclusively difunctional organic components which are usually not readily accessible and are generally expensive. The process is not suitable for producing siloxane polymers which are organically substituted at lateral positions. Commercially available copolymers of dimethylsiloxy and hydrogenmethylsiloxy units are usually methyl-terminated. Although these raw materials are highly suited for the modification with aliphatically unsaturated organic compounds, the production of high-molecular-weight siloxane polymers is made very much more difficult by the unreactive siloxane backbone after the hydrosilylation step.